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At least 289 records · Page 16Linked to original sources
PubMed1993

A test of exercise analgesia using signal detection theory and a within-subjects design.

Evidence for the existence of exercise-induced analgesia has been weak, inconsistent, or anecdotal. The present study addresses criticisms of previous research by using a signal-detection analysis of pain perception in a within-subjects, repeated-measures research design with 22 endurance athletes who exercised in a naturalistic setting. Analysis showed discriminability measures from the lower intensities of a radiant-heat pain-perception task were significantly lower after exercise than the subjects' discriminability after a no-exercise period. This is consistent with discriminability decreases seen in studies of subjects who are under the influence of analgesic chemicals such as morphine and nitrous oxide. Discriminability differences were not seen in this study at the higher intensities of the stimulus, suggesting that exercise generates perceptual changes that may not reach pain-mediating levels. Visual analogue data suggest cognitive and motivational factors also play a role in report of pain after exercise.

Adult↗
PubMed2002

[Signal detection theoretical aspects of various threshold detection procedures].

Psychoacoustic threshold detection measurements are widely used in clinical and research applications. A variety of procedures has been described to measure psychoacoustic thresholds. Each of these procedures has advantages and disadvantages. For clinical purposes procedures providing fast results may be preferred whereas for psychoacoustic research the threshold has to be determined as exactly as possible. Conventional procedures are based on a yes/no paradigm. Since these procedures are influenced by criterion shifts, n-alternative forced choice procedures were developed. Here the patient has to indicate the interval most likely to contain the signal. Additionally, it is possible to estimate the threshold based upon few data and comparing these to known psychometric functions. Following an overview outlining procedural aspects of threshold detection methods aspects of signal detection theory in relation to these procedures are discussed. Signal detection theory may help to explain why results obtained with various procedures may be quite different.

Audiometry, Pure-Tone↗
PubMed2004

Embolic Doppler ultrasound signal detection using discrete wavelet transform.

Asymptomatic circulating emboli can be detected by Doppler ultrasound. Embolic Doppler ultrasound signals are short duration transient like signals. The wavelet transform is an ideal method for analysis and detection of such signals by optimizing time-frequency resolution. We propose a detection system based on the discrete wavelet transform (DWT) and study some parameters, which might be useful for describing embolic signals (ES). We used a fast DWT algorithm based on the Daubechies eighth-order wavelet filters with eight scales. In order to evaluate feasibility of the DWT of ES, two independent data sets, each comprising of short segments containing an ES (N = 100), artifact (N = 100) or Doppler speckle (DS) (N = 100), were used. After applying the DWT to the data, several parameters were evaluated. The threshold values used for both data sets were optimized using the first data set. While the DWT coefficients resulting from artifacts dominantly appear at the higher scales (five, six, seven, and eight), the DWT coefficients at the lower scales (one, two, three, and four) are mainly dominated by ES and DS. The DWT is able to filter out most of the artifacts inherently during the transform process. For the first data set, 98 out of 100 ES were detected as ES. For the second data set, 95 out of 100 ES were detected as ES when the same threshold values were used. The algorithm was also tested with a third data set comprising 202 normal ES; 198 signals were detected as ES.

Algorithms↗
PubMed1979

Chlordiazepoxide-induced disruption of discrimination behaviour: a signal detection analysis.

To assess the effects of chlordiazepoxide (CDP) on a stable discrimination performance, eight rats were trained on a simple brightness discrimination and injected with three dosages (0, 5, and 10 mg/kg) once performance was stable. Signal detection analysis of the results was used to differentiate sensory from motor/responsivity effects of the drug. At 5 mg/kg, CDP increased general responsiveness which is consistent with the hypothesis that CDP disinhibits responding. At 10 mg/kg, however, this effect on responsivity was reversed and there was also a suppression of stimulus sensitivity.

Animals↗
PubMed1993

Information processing by tree fellers: signal detection analysis.

Eighteen experienced tree fellers and eighteen forestry students watched video recordings of mature eucalypts being felled by a man using a chain saw, and then rated whether each tree had fallen normally or abnormally. Signal-detection analysis showed that the tree fellers were more accurate than the forestry students in predicting eventual outcome. Further, the tree fellers achieved peak accuracy in discrimination by the time the logger had completed cutting the scarf (typically several minutes before the tree hit the ground), whereas the forestry students predicted outcome most accurately only when a tree was falling (and about 1 s from hitting the ground). Study of the bases for information processing and decision making by tree fellers has implications for personnel selection and training, as well as for formulation of effective work practices.

Adult↗
PubMed2005

Postnatal ethanol exposure disrupts signal detection in adult rats.

Human prenatal ethanol exposure that occurs during a period of increased synaptogenesis known as the "brain growth spurt" has been associated with significant impairments in attention, learning, and memory. The present experiment assessed whether administration of ethanol during the brain growth spurt in the rat, which occurs shortly after birth, disrupts attentional performance. Rats were administered 5.25 g/kg/day ethanol via intragastric intubation from postnatal days (PD) 4-9, sham-intubation, or no intubation (naïve). Beginning at PD 90, animals were trained to asymptotic performance in a two-lever attention task that required discrimination of brief visual signals from trials with no signal presentation. Finally, manipulations of background noise and inter-trial interval duration were conducted. Early postnatal ethanol administration did not differentially affect acquisition of the attention task. However, after rats were trained to asymptotic performance levels, those previously exposed to ethanol demonstrated a deficit in detection of signals but not of non-signals compared to sham-intubated and naïve rats. The signal detection deficit persisted whenever these animals were re-trained in the standard task, but further task manipulations failed to interact with ethanol pretreatment. The present data support the hypothesis that early postnatal ethanol administration disrupts aspects of attentional processing in the rat.

Animals↗
PubMed1989

Effects of copper and vitamin B-6 deficiency on taste sensitivity in the rat: a signal detection analysis.

The effects of dietary copper and Vitamin B-6 deficiency on NaCl sensitivity in adult male rats were assessed in separate studies using a double-blind protocol, high-precision gustometry, computer-controlled go/no-go operant procedures and signal detection measures of sensitivity and responsivity. The dietary manipulations reduced plasma copper ion content to 40% of baseline levels in the copper deficient group and plasma 5'-pyridoxalphosphate content to 5% of baseline levels in the Vitamin B-6 deficient group and, as expected, altered hematocrit and hemoglobin levels in both groups. These metabolic changes resulted in increased NaCl preference in the Vitamin B-6 deficient group but did not alter sensitivity or responsivity to NaCl, and similar results were obtained in simple and complex taste discrimination tests. The present results demonstrate that dietary copper and Vitamin B-6 deficiencies do not result in altered taste sensitivity in the adult male rat.

Animals↗
PubMedDate not supplied

Measurement of visual sustained attention in schizophrenia using signal detection analysis and a newly developed computerized CPT task.

Sustained attention in schizophrenia was assessed with a newly developed, computer-controlled, modified version of the continuous performance test in which specific attentional effects can be empirically distinguished from nonspecific factors by signal detection theory (SDT). Results indicated that patients showed a more rapid decline in specific attentional, but not nonspecific processes, as measured by SDT parameters of A' and B", respectively.

Adult↗
PubMed2006

Characteristics associated with discharge to home following prolonged mechanical ventilation: a signal detection analysis.

The objective of study was to identify characteristics associated with being home at 6 months in 80 patients on prolonged mechanical ventilation (PMV) (> or =7 days). At 6 months, 47.5% were home, 13.8% institutionalized, and 38.8% deceased and classified "not home." Using signal detection methodology (SDM), four mutually exclusive groups at high and low probability of being home were identified. The best outcome (94.4% home) was achieved by patients with an admission Charlson Comorbidity Score < or =3 and an Acute Physiology Score (APS) < or =21 and the worst outcome (23.4% home) by patients with an admission Charlson Comorbidity Score >3 and Health Assessment Questionnaire score >2.7. SDM provided an effective means of identifying subgroups likely to be discharged home using available information.

Activities of Daily Living↗
PubMed1983

Effects of sleep deprivation on signal detection measures of vigilance: implications for sleep function.

In an attempt to tease out the extent to which the performance decline during sleep deprivation might be due to a fall in the inherent capacity (d') of a subject, the parameters of the theory of signal detection were applied to auditory vigilance data obtained five times per 24 h during 60 h of continuous wakefulness. Eight subjects were exposed to both control and deprivation conditions in a balanced design. Oral temperature and self-assessed alert-drowsy reports were taken at three hourly intervals. The value of d' exhibited a significant stepwise decline during deprivation, falling sharply within the usual sleep period and levelling out during the daytime. Both temperature and self-assessment data exhibited clear circadian rhythms overlying the declines due to deprivation. The changes in d' were seen to be consistent with a brain "restitutive" role for sleep function.

Adult↗
PubMed1987

Effects of head restraint on signal detectability in simultaneous and successive vigilance tasks.

Dittmar, Warm, and Dember (1985) suggested that visual parallax may lead to declines in perceptual sensitivity over time in spatial vigilance tasks involving comparative judgments. The present study tested this possibility by restraining subjects' head movements during a 1-hr vigil in which comparative (simultaneous task) or absolute (successive task) judgments of line length were necessary for signal detection. Under free-viewing conditions, perceptual sensitivity declined over time with both types of tasks. Head restraint eliminated the sensitivity decrement in both cases. The results highlight signal quality as a crucial determinant of perceptual decrements in sustained attention.

Attention↗
PubMed1981

P3 latency in threshold signal detection.

The EOG, EEG(Cz, Pz) and response latencies were obtained from ten subjects in an auditory threshold detection task with a signal probability of 0.5. In order to minimize any interaction of signal condition (signal-presence vs. signal-absence) and uncertainty about the moment of signal occurrence (temporal equivocation), the observation period was marked with a cue light. The single-trial latencies of the P3 component associated with correct signal-present and signal-absent decisions were assessed on the basis of the cross-covariance functions of the EEG epochs and a template of the P3. Trials with values of covariance smaller than a criterion value were discarded. The mean and dispersion of the P3 latency proved larger for signal-absent than for signal-present trials, while the mean values of covariance were smaller for signal-absent than for signal-present trials. In addition, the mean and dispersion of the P3 proved smaller for high confidence than for medium confidence signal-present trials. Nearly all these effects also proved significant for the response latency. The single-trial P3 latencies were positively correlated with the response latencies of the same trials. The observed latency variations of the P3 were interpreted in terms of changes in the detectability of the stimulus events. It was concluded that the signal condition had a significant effect upon the latency of the P3 associated with signal-present and signal-absent decisions over and above that due to temporal equivocation.

Adult↗
PubMed1978

A critical examination of the use of signal detection theory in evaluating a putative analgesic--transcutaneous electrical nerve stimulation.

Experiments using normal human subjects were performed to determine the effect of a putative analgesic, transcutaneous electrical nerve stimulation (TENS), on the perception of noxious thermal stimuli and also to examine critically the general applicability of signal detection theory (SDT) to the evaluation of analgesic agents. In order to provide a control for factors related to suggestion, subjects were assigned to groups in which real or sham TENS was administered. It was shown that previously suggested criteria for demonstrating actual analgesia using SDT should be reevaluated. First, discriminability changed in one of the sham groups, suggesting that discriminability can be affected by changes in mental state which may occur during the evaluation of an analgesic. Secondly, criteria changed without accompanying changes in discriminability; this was interpreted as reflecting actual analgesia, rather than only changes in response bias, produced by TENS.

Adult↗
PubMedDate not supplied

An approach to single trial analysis of event-related potentials based on signal detection theory.

The aim of the present paper was to introduce a single trial analysis to event-related potential measurement in order to illuminate the mechanisms behind an impaired P300 amplitude occurring under certain experimental conditions. For this purpose we applied tools from linear system theory and signal detection theory to single trials in an oddball paradigm in order to estimate the amplitude of the positive deflection around the P300 latency following target and nontarget stimuli. According to the density functions of these amplitude distributions we operationally defined 'P300 absent in target' (P300 amplitude smaller than an individual threshold under target conditions) as well as 'P300 present in nontarget' (amplitude greater than the threshold under nontarget conditions). Our approach appears to be appropriate to differentiate between an overall reduction of single trial event-related potentials and seldom elicited P300s.

Adult↗
PubMed1981

Attention in schizophrenia. Signal detection in the visual periphery.

Earlier evidence has suggested a differential deficit in visual preattentive processes in schizophrenia. An understanding of the level of information processing at which such deficits might occur and links to a possible structural basis for such deficits were sought in an investigation of signal detection in the visual periphery. Acute and chronic schizophrenics alternatively classified as paranoid or nonparanoid and normals were tested in a task requiring simultaneous discrimination of foveal targets as well as detection of peripheral targets at either of two display angles where the use of scanning eye or head movements was experimentally controlled. An analysis of peripheral sensitivity indicated that chronic and particularly nonparanoid subjects were less able to detect peripheral targets than acute or paranoid schizophrenics and normals. An analysis of criterion indicated that paranoid subjects tended to be more conservative in the most difficult detection condition. Corresponding analyses of trial validity and response latency yielded no results indicative of systematic differences in motivation. Differences in sensitivity were therefore attributed to a deficit in early preattentive processes. The performance of nonparanoids also raised the question of differences in midbrain activity associated with the processing of ambient visual information.

Attention↗
PubMed1989

The use of signal detection theory to assess DSM-III-R criteria for autistic disorder.

Sixty cases from the DSM-III-R field trials for autistic disorder (AD) were studied to derive an optimally sensitive and specific combination of scoring criteria based on the 16 DSM-III-R criteria for AD. Signal detection theory, a statistical method new to psychiatric research, was applied. Two of the sixteen criteria tested with this methodology yielded a sensitivity of 0.82, a specificity of 0.89, and a total predictive value of 0.91 relative to clinical diagnosis. Excluded criteria were redundant; unrelated to diagnosis; or highly correlated with degree of mental retardation, mental age, and/or chronological age.

Adolescent↗